I am working with air coils and would like to reverse polarity automatically and at a high rate per minute. Say 1500 times a minute. Can this be done? And how if so. Any help would be appreciated. Air coils are on activated by infrared emitters through a timing wheel. The duration is 52 degrees, and I would like to reverse polarity half way through at 26 degrees.

I am using air coils to effect change on magnetic lines. Initially I want the air coil to attract a magnet. And then halfway through its cycle, I would like to change the polarity and push the magnet away. This would be happening at a high rate of about 1500 to 2000 times a minute if it were possible. I am using the air coils to get movement between a 6" ring magnet and two 1.5" disc magnets. But was trying to achieve a pull push with the same coil to create more force. My plan for the timing system was infra red emitters mounted directly above photo sensors. The emitters would only be able to communicate with photo sensors briefly through a opening in the timing wheel. Activating the air coils. This opening is 54 degrees of the possible 360 degrees of the wheel. I would like to make the first 26 degrees a pull. And then switch to a push for the remaining 26 degrees of duration. This is the first timing system I want to build. Once I get it working, I would like to rework timing system to something more computerized. As much as I am trying to make this work. I am also trying learn as much as I can through this. I am a 42 yr old hobbyist, making a life change. I am working on my first year electrician ticket. I have got things moving between the magnets but have to rework coils as there would be too much heat created and not enough dissipation. Coils are creating 38 watts. And not enough surface area for cooling. I believe it should be .5 watts per square inch for heat dissipation. Can you confirm this as well?
Thx for your time. Sorry if this is not what you needed. Timing system is still in my head as I have been focusing my attention on the coils and I am not really ready for it yet. But had this idea last night. And wondered if it were even possible.

OK, I'm a little closer but a picture would still be worth a thousand words.

If I understand it, you want to put a 25-30Hz alternating current into your coil, with the exact timing depending on the feedback signal coming from your photo sensor. (I really don't grasp that connection, but maybe that's OK.) What voltage and current are we talking about?

For many push-pull applications, such as a reversible DC motor, a circuit called an H-bridge is used. Lots and lots of threads on H-bridges here. Switching an H-bridge at 30Hz should not be to big a problem. Try looking around for H-bridge motor controllers.

MOSFETs are used as the switches in an H-bridge, and they are controlled by the voltages appearing on their gate pins. Choosing the MOSFETs will depend on the voltages and currents you need to switch.

The reason for infra red emitters and photo sensors is that I am an engine builder/hot rodder, and it was a simple timing system for me to get started. When the emitters and photo sensors line up with the start of the timing opening in the timing wheel. One of the two disc magnets are halfway between one of the seven coils placed on 6 inch disc magnet. This would turn coil to on/pull. For the first 26 degrees of duration. At 26 degrees the disc magnet would be 2 degrees past top dead ctr of coil. At this point is when I would like to reverse polarity to go from pull to push . As the disc magnet reaches the end of the cycle of pull push for that coil. It starts all over again for the next coil. Once I have that working in something I understand. That is when I want to move on to your suggestions. I am still working on a better coil though. Was I correct in the heat dissipation?
Thanks again
Almost forgot. I am using a 9 volt battery. My coil resistance right now is 2.2 ohms. But that will be changing.

2 problems: You can't get a pound of power out of an ounce of battery, and automotive discussions are not allowed on this site. A moderator will be along soon and guide you to a better site for your work.

Dude this is 100 percent electrical. Just because I mentioned I was into cars and was drawing from that experience does not mean it has to do with cars. I appreciate the other guys opinion. But you seem to have a negative attitude. I am apprenticing as an electrician first year making a big change at this time in my life. I am 42. Everything I am doing in my garage in my time. Succeed or fail, is interesting to me. And I am learning a lot because I am interested. Now with what was passed on to me before you. I can go read up on H bridges. Get some sort of understanding of it. Experiment with it and learn from it.
I really don't understand how you figure this is an automotive application.
You sound bitter

Whoa, relax. Both things #12 pointed out are true. A 9V battery driving a large coil is just not practical. And this forum has Terms of Service that prevent many topics.

Safety is important around here and because so many posters intentionally hide their questionable activities, long-timers here have learned to be skeptical, and to keep asking questions until we're satisfied that the OP (original poster) is not a risk to himself or others. (And to avoid wasting time working on the wrong problems.) Sometimes it's just a misunderstanding because we're not all clear writers, but sometimes it's some kid building a real threat.

Your project is still very foggy (to me, anyway) and I had to re-read your post a few times to see that it may not be automotive. You can forgive #12 for not catching that the first time thru. But then it starts to read a little like you could be building a rail-gun, another topic not allowed here.

I suggest that you read up a bit on BLDC (Brushless DC) motors and how they work; which seems to be basically what you're interested in doing. BLDC motors are everywhere nowadays - and it might surprise you to learn that the fan motor(s) in your computer are BLDC-based!

You mention IR emitters - you might consider using Hall-effect sensors instead, as IR emitters/receivers will stop working when contaminated with dust/crud/mud/any opaque foreign objects. That's what BLDCs generally use.

I don't know what a rail gun is LOL. Something else to look up. I know about the battery being two weak. My intention was to build a small generator further down the shaft and the battery would just be for a kick start of the system. With hopes of being a perpetual motion machine. I know I am reaching for the stars. But it's a hobby that plays right into my new profession. If I hadn't taken my first year of schooling already. I would not have had as much understanding of the magnetic fields. I have a crude test bench made up. The 6 inch magnet is attached to plywood . 1/2 inch shaft through ctr. There are 2 1 1/2 inch disc magnets mounted above in the rotor. I have 3 of the seven coils placed over 6 inch magnet next to each other. I wired each coil to a momentary switch. 3 switches in total. And operated in sequence to move rotor half way around. Then I had idea about reversing polarity half way through. I got 3 more switches and 6 relays and wired the 3 coils both ways. So that one engaged first button coil was powered to pull and when hit second button relays switched polarity to give a push and it moved considerably faster. My problem that I have to overcome at the moment. Is making a coil strong enough to work on magnetic fields and not get too hot. My current coil is 38 watts. And I still have that question about cooling. Is it .5 watts per square inch? And if so is that for free standing air? Could that number go higher with air cooling with vents put into rotor? I am really learning a lot. And I am enjoying what I am doing. Even though my chances of success aren't great. If I can solve coil problem I have CNC machine shop willing to donate there time to make them for me. I just have to pay for material. Hopefully this makes you feel a little better about who I am and what I am trying to accomplish. I wasn't forthcoming to start with because it is pretty far fetched. And I get enough negativity. I am not asking anybody to agree with me or figure it out for me. I just want to be free to try. And to be able to ask the questions that pop up along the way from people with more knowledge then me.
Sorry for any confusion
Thx again

I bad. I will never mention it again. But don't ask if you don't want to know. I didn't bring it up in the first place. I was asking a question, and made no mention of my hobby. It was a legitimate question. Now I am learning something new. And it all improves my knowledge base. Be it success or failure. I am growing and learning. So does anyone have an answer about the heat dissipation? Is it .5 watts per square inch? Is that for free standing air? Or will that number go up with air movement?

I am really learning a lot. And I am enjoying what I am doing. Even though my chances of success aren't great.

Click to expand...

Your chances are precisely zero. But the those first two sentences trump it all. By all means carry on. As long as you're not trying convince anyone of your over-unity success, and instead focus on minimizing known losses, I think you're OK here. (Don't take my word for it, though.)

Something to ponder on the theoretical side: If you know that heat is being carried away by the air, how can this come close to being a perpetual motion machine? That heat is energy that had to come from somewhere within the system (your battery), and it's not being harnessed. The best "perpetual" motion machines convert energy from one form to another back and forth with minimal losses. They never get past unity but some clever designs are able to reduce losses to a low percentage.

I am not trying to convince anyone nor do I want to. I am not even interested in talking to anyone else that is working on something similar.i don't have the patience. So I can understand it not being welcome here. But by building this. Learning about Air coils, H bridges. Reversing polirarity. The connection between 1500 times per min and 25hz. 555 MOSFET timers infra red emitters. Photo sensors. Auto cad, Bldc motors. Thx wookie. Building a working generator at the other end of this thing. In the end I will have a working knowledge of these and a few other things that pop up along the way. And will be able to build on that for the future. I should also have mentioned I have been on disability since January. And will be for a couple more months(ruptured quad muscle). I AM BORED. And this occupies my time.